Car cover
That pic with 3 sails is 2 kites and an A-kite I think- but none of them are bloopers.
Morgan is right- they were built to be flown opposite a sym spinnaker at app wind angles deeper than 160 or so. The theory was that for IOR type boats with very high aspect rigs and tall skinny mains, they would help with overall sail area, "stabilize" the boat from rolling in big air (never really worked out that way), and probabaly most important (and the only tangible benefit they provided), they would help "push" you a little deeper-so that as long as it was not slowing you down (which they often did if not flown perfectly), you could "net" slightly better downwind VMG-sort of like induced leeway-a good thing when working downhill.
One key reason they were used on race boats for a while was that they were rated as headsails under the IOR-not spinnakers, so we thought we were getting "free' sail area downwind...
Having said that, it is established that they are more trouble than they were worth-rarely helped performance, and limited maneuverability. My "proof" for this as being "established" is because us sailmakers stopped selling them-even for those who asked for them in the years following their "fall from grace". As a "recovering" sailmaker, I can tell you that if we felt we could make $ with those sails (and still look at ourselves in the mirror), we would have.
It was our industry that really first came to terms with what a waste of time they were/are..
They DO superficially resemble cruising Spinnaker/Gennakers, and can be used (no pole needed) for this purpose if you are goofing around. They are not nearly as good, because they are shaped SUPER full for the original purpose (DDW)-so at angles closer than about 140-150 app (if using it as a gennaker) it is too deep to be effective at typical sailing angles-especially when compared to a real A-spin or cruising spin/gennaker. So don't expect it to be a substitute for the real thing-they are designed totally differently.
Use it for something else-but if you want to fool with it more, I can give you some specific instructions on how to fly it opposite the kite-just let me know.
Cheers
S